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278 OSTRICH NUTRITION AND MANAGEMENT J. J. du Preez SUMMARY In spite of the relatively long involvement of agriculturalists with the ostrich (Struthio camelus) as a domesticated bird to produce food and other commodities, only a small, volume of published information on nutrition and management exists. More information is available on topics such as physiology, ecology and practical aspects like artificial incubation. A summary of the scant information on nutrition and management is given in this paper and it is attempted to fill the gaps with theoretical predictions for practical quantitative feeding of growing and breeding birds. Remarks are made on research priorities to put ostrich farming on a sound scientific basis. INTRODUCTION Ostrich farming probably had its origin when an unknown spectator was surveying birds in the open Savannah performing an ambulant display of waltzing, an act of behaviour after periods of tension, according to Hurxthal (1979) and Wood-Gush (1967). The plumes of these ostriches caught the eye of the observer. He became the first entrepreneur who decided to make it his business to hunt these creatures. The vain vision he had was a decor of plumes surrounding and adorning a group of chorus girls performing a jubilant dance to the music of Offenbach. The hunters and many after them did not fully understand the behaviour responses of ostriches but it was discovered in time that these birds need not be hunted because they could be confined to a farm and earn a living for the "owner". The fashion plume market flourished in the late 1800's. Today we still want to know more about the behaviour of ostriches since it may help us to improve management and enhance production of exotic items which now include hides and meat. It will be attempted in this paper to review the present knowledge on the management and nutrition of ostriches and to point out many areas where information is lacking. NUTRITION AND MANAGEKfWl? OF YOUNG BIRDS A model to form the skeleton for nutritional research To imitate the feeding pattern of the bird in the wild would be one way of feeding ostriches in captivity. The nutritionist could use a different approach by studying the growth of the bird and then attempt to predict it's growth. By applying mathematical skills, basic nutritional knowledge and using chemical analyses, the nutritionist could then postulate the nutrient requirements of the birds. These hypotheses can be tested experimentally. This is perhaps the point in the development of nutritional standards for ostriches that we are at now. The growth of ostriches from three regions in Southern Africa, covering an area in which most of the ostrich population in the world occurs today, has been studied (Du Preez, Jarvis, Capatos and De Kock 1990a). These curves are shown in Fig. 1. Department of Poultry Science, University of Stellenbosch. Stellenbosch, South Africa.
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Page 1: OSTRICH NUTRITION AND MANAGEMENT

278

OSTRICH NUTRITION AND MANAGEMENT

J. J. du Preez

SUMMARY

In spite of the relatively long involvement of agriculturalists withthe ostrich (Struthio camelus) as a domesticated bird to produce food andother commodities, only a small, volume of published information onnutrition and management exists. More information is available on topicssuch as physiology, ecology and practical aspects like artificialincubation. A summary of the scant information on nutrition and managementis given in this paper and it is attempted to fill the gaps withtheoretical predictions for practical quantitative feeding of growing andbreeding birds. Remarks are made on research priorities to put ostrichfarming on a sound scientific basis.

INTRODUCTION

Ostrich farming probably had its origin when an unknown spectator wassurveying birds in the open Savannah performing an ambulant display ofwaltzing, an act of behaviour after periods of tension, according toHurxthal (1979) and Wood-Gush (1967). The plumes of these ostrichescaught the eye of the observer. He became the first entrepreneur whodecided to make it his business to hunt these creatures. The vain visionhe had was a decor of plumes surrounding and adorning a group of chorusgirls performing a jubilant dance to the music of Offenbach. The huntersand many after them did not fully understand the behaviour responses ofostriches but it was discovered in time that these birds need not be huntedbecause they could be confined to a farm and earn a living for the "owner".The fashion plume market flourished in the late 1800's. Today we stillwant to know more about the behaviour of ostriches since it may help us toimprove management and enhance production of exotic items which now includehides and meat. It will be attempted in this paper to review the presentknowledge on the management and nutrition of ostriches and to point outmany areas where information is lacking.

NUTRITION AND MANAGEKfWl? OF YOUNG BIRDS

A model to form the skeleton for nutritional research

To imitate the feeding pattern of the bird in the wild would be oneway of feeding ostriches in captivity. The nutritionist could use adifferent approach by studying the growth of the bird and then attempt topredict it's growth. By applying mathematical skills, basic nutritionalknowledge and using chemical analyses, the nutritionist could thenpostulate the nutrient requirements of the birds. These hypotheses can betested experimentally. This is perhaps the point in the development ofnutritional standards for ostriches that we are at now.

The growth of ostriches from three regions in Southern Africa,covering an area in which most of the ostrich population in the worldoccurs today, has been studied (Du Preez, Jarvis, Capatos and De Kock1990a). These curves are shown in Fig. 1.

Department of Poultry Science, University of Stellenbosch. Stellenbosch,South Africa.

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Although small samples of populations were used, significantdifferences in the rate of growth between birds from different regions andsex differences were shown to exist. Continuation of this work isanticipated. In recent work Degen et al (1990) described a growth curveof ostriches (mixed sexes). It resembles very closely the growth ofNamibian birds illustrated in Fig. 1. The theoretical amino acidrequirements of Namibian male birds were calculated (Du Preez et al 1990b).The requirements of Oudtshoorn males were subsequently calculated and theseresults will be presented as an illustration of hypothetical requirementsfor lysine and sulphur-containing amino acids (SAA) during the normaldevelopment under non limiting conditions from hatching to maturity. Thedata presented in Tables 1 and 2 were used to make these calculations.They were obtained from carcass analysis performed on ostriches from birthto maturity to gain information about the development of chemicalcomponents of the body during growth. The sacrificed birds weredefeathered and the empty body (contents of intestinal tract removed) wasanalysed for moisture, ash, protein and lipid. The dry, lipid-free sampleswere also analyzed for amino acids. The results in Table 2 made afundamental contribution to the predictions of requirements for aminoacids, but because of the absence of replicate samples at each age or bodysize, the variation in protein, lipid and ash composition could not bedetermined. A growth function for protein could not be fitted to the data.The data relating to the mature bird (Table 1) were essential in thecalculations to be illustrated here. Because growth curves of the sexesdiffer, carcass analyses should be performed for each sex separately. Atthis point in time the results of analysis of only male birds are availableas presented in Tables 1 and 2. Lysine and the sulphur containing aminoacids, methionine and cystine will be concentrated on to illustrate therequirements for them graphically.

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Table 1 Composition of defeathered male ostrich carcasses

Table 2 Amino acid composition of ostrich defeathered empty carcasses ofmale birds (g/l6gN)

To calculate the amino-acid requirements, protein accretion in thebody was used as the fundamental system as explained and used by Emmans(1988) for turkeys. The coefficients used in the calculation to convertdietary amino acid, lysine and SAA to body amino acid were 0.73 and 0.63respectively. The value of the coefficients had in different instancesbeen determined for poultry (Fisher and Emmans 1982). Since values are notavailable for ostriches, the poultry values were used. Discrepanciesbetween the estimated and experimentally determined lysine and SAArequirements for ostriches would in effect be these coefficients comingunder scrutiny. From unpublished results using poultry it would appear thatthe coefficients for lysine and SAA are not equivalent. The assumedprotein in the animal at maturity would have an influence on the estimatedamino acid requirement. In our calculation we relied on a single birdanalysis and no account could be given of the confidence limits of theestimates. It needs to be pointed out though that the ratio of protein toother body components is the concluding factor and this particular birdreached a constant body mass and was consuming a maintenance diet,

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excluding superfluous lipid deposition at the time of slaughter. Theestimated protein required for maintenance was calculated, using theformula suggested and applied by Emmans (1988), which is as follows:

Calculated estimates of the daily lysine and SAA requirements ofgrowing ostrich males are shown in Figures 2 and 3.

IW’IMA’I’IW R115OUI REMI3N’I OF OS’I’RICII MALE FOR SAA(OUD~SII~ORN SIQCK) gram / bird /day

FIG. 3

The work published by Swart and Kemm (,1985) refer to protein requiredby ostriches between the body weight intervals of 60 to 110 kg. Lysine was5 % of the protein in the experimental diets . The highest gain of 235 gper day occurred when birds were consuming approximately 2.2 kg per day ofa diet containing 14 % protein, thus 15.2 g lysine per day. Gandini et al

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(1986) found that ostrich chickens in the weight interval 1 to 9.5 kg (10 dto 56 d) receiving a diet containing 20 % protein showed the superior feedconversion. The calculated mean lysine intake was 2.73 g per bird per day.The average mass gain of these birds was 163 g per day while consuming anaverage of 275 g diet per day. The lysine input in the latter report is inaccordance with the estimated value for young growing birds. However thelysine input of 15.2 g / day in the work published by Swart et al (1985)seems very high, indicating a possible imbalance of amino acids in thatdiet. As yet it has not been proven that lysine is an essential amino acidto the ostrich as had been shown for poultry. Since metabolism and growthof male and female ostriches differ, researchers may use the techniquepublished by Gandini et al (1985) to separate the sexes at an age of 3weeks by cloaca1 examination.

Brooding and rearinq

The young chick does not possess an egg tooth and grows its way outof the relatively strong egg shell possibly aided only by its strong legsand using its third phalange. It can survive without food and water forsix or more days depending on its egg yolk reserves. It is recommended thatduring this period the birds learn to find the food and water which shouldbe easily accessible. Warmth is essential for young ostrich chickens. Thetype of heat source normally supplied for poultry can be used andtemperatures similar to that for chickens (Michie 1977) are recommendedfor ostriches during the first 4 weeks after hatching . Floor area neededby growing ostriches depends on the type of housing. Semi-intensiverearing of birds is the most widely used method and even during intensivekeeping of ostriches in controlled environment houses it is advisable tolet them out to minimize occurrence of leg problems (Guittin 1986 ). Theideal floor area for ostriches will have to be studied using criteria otherthan economics and yield of product. General consensus concerning optimalpopulation density is not easily found in conclusions drawn from studieswith poultry. There is no definite connection between what farmers and someresearchers interpret as "perform well" and freedom of stress (Thorpe1967). The preferred norms should be to compare the behaviour of thewhole intact animal in the wild with that in captivity and to note actionssuch as acoustic and visual communication, preening, cannibalism(redirection activity), abnormal corpophagy and suppression of anyinstinctive abilities (Wood-Gush 1967). The most economic optimum stockingdensity of broiler birds is usually higher than the density shown to beideal for maximum mass gain. The latter is approximately 30 kg live mass(17 birds) per square meter in environmentally controlled houses (Shanawany1988), and half of these values should be used in houses ventilated byconvection. These values should not be directly applied to ostrichesduring rearing, rather keeping in mind the sensitive nature of thisspecies, even after years of "domestication". The first reaction of ananimal to a potentially hostile situation is a change in circulationdynamics and it has been suggested that a rise in deep muscle temperature,indicating active vasodilation, could be used as a measure of the defensereaction, exhibited during stress (Draper and Lake 1967). The normalcloaca1 temperature of the adult ostrich is 39.3 OC (Crawford et al 1967).A diurnal cycle was elaborated on by Louw et al. (1969). Stocking densitygoes hand in hand with ventilation rate. In fact specifying floor area ismeaningless without the assumption that ventilation and for that matterfeeding and drinking facilities are.sufficient. Once the optimalpopulation density of birds is established the ventilation standardsapplicable to poults and poultry could be used with less chance of errorfor ostrich chickens. The general rule of thumb is 4 m3 per kg live mass

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per hour (Tilley 1967 ), with the appropriate minimum and maximum rates ofventilation during respective low and high outdoor temperature conditions(Charles et al 1981). Dim light causes chickens to be docile and 5 lux(lumen&q meter) is normally recommended in broiler houses. If light hasa similar effect on young ostriches it would be beneficial to apply thisprinciple. Feeding space of 4 cm/kg live mass and water space 20% of thatwould also work with ostriches. Raising the feed level to correspond tothe back height of the bird would also save energy and prevent food wastageas it does for poultry.

Peed intake

Assuming that ostriches are kept in such circumstances that theirenvironmental heat demand is met and the efficient energy system (EE)(Emmans 1984) is used to adjust the ME of the diet, an estimate can be madeof the daily feed allowance to meet it's energy needs. The major energyrequirement is that used for maintenance. A formula proposed by Emmans(1988) was used to predict the maintenance requirement :

where MH is maintenance heat (MJ / day)Pm is mature body protein mass (kg)u is P/Pm and P = body protein mass (kg)

Estimates of the daily gain in protein and lipid, generated from thegrowth curve equation, was converted into energy required daily inkilojoules. This was added to the maintenance requirement to arrive at atotal energy requirement to which the energy for activity and locomotionwas added. To convert lipid and protein gain into EE requirement (MJ /day) values of 56 MJ / g lipid 50 MJ / g protein were respectively used asexplained by Fisher 1987.

In Fig.4 the expected intake of EE is graphically illustrated and inFig. 5 an estimated feed allocation is shown using the EE contents of diets(MJ per kg) that would normally be formulated for birds at different ages.(body weights).

FIG.4

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The greatest lack of information lies in the nutritional values offeedstuffs used in diet formulations for ostriches. Few attempts were seenwhere an evaluation of ingredients has been undertaken. Energy values ofdiet components are essential for prediction of feed consumption. Thewater requirement of ostriches was determined and reported by Withers(1983). It amounted to 8 liters/day under experimental conditions foradults while the birds were feeding on dry alfalfa (5 kg per day). In theexperiment reported by him, deprivation of water caused feed intake to dropby 84 percent. The ratio of water consumption to dry matter feed intakeaccording to Degen et al (1991) was nearly constant at 2.31.

NUTRITION AND MANAGEMENT OF ADULT BIRDS

Breedinq bird manaqement

Most birds are slaughtered at 12 to 14 months of age, after the firstfeather crop has been harvested, to produce a hide which accounts for 75%of .the income and meat accounting for another 15%. The first selection ofbirds destined for breeding is done at this point in time. A surplus ofanimals, which could be slaughtered later subsequent to selection ofproductive pairs, should be allowed for. Wild ostriches require 3 or moreyears (males 4 years) to become sexually mature (Hurxthal 1979). The malesshow a flush of pink skin pigmentation in the anterior of the tarso-metatarsal limb and the beak. While the females are stimulated to sexualactivity by the former and other, mostly visual, courtship activities bythe male, both sexes would be stimulated by an abundant supply of foodbefore the breeding season. Breeding is seasonal as can be seen from thegraph shown in Fig. 6. The breeding season usually starts in winter andshows a fluctuating pattern due to egg production cycles which mostindividual females exhibit.

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Days from start of production cycle

Fig. 7 Natural pattern of lay of wild ostriches,13 female pairs, one male per pair

On average a female lays 15 eggs, one every second day then takes arest (pause) for 7 days. This pattern is illustrated in graph (Fig. 7)generated from a sample population of 26 females (13 pairs).

In practice one male would be placed with each pair of females in abreeding paddock of a quarter hectare. It will be noted in Fig. 7 thatover a period of 147 days (21 weeks) three peaks emerged at about 49 dayintervals. This corresponds with field observations reported by Jarvis etal (1985). They noted three peaks of egg production in 150 days. At the

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end of the last peak ostriches in the wild would gradually stop laying butdomesticated birds would continue laying at a slow rate during midsummer,showing a slight peak in February before egg laying is discontinued untilthe next winter. The predicted number of eggs from the 26 females in 3822potential days was calculated to be 940 (24,6%). Since the ostrich lays anegg every second day the percentage could be doubled i.e. 49.2% to comparewith that of poultry. Jarvis et al (1985) suggested a method to estimatethe number of productive females in a breeding season. The estimate was 22productive females in this model flock which increased the production from49.2% to 58%. The number of eggs per female per season is a more practicalnorm to work with and these calculations predict 36 and 42 eggs per femaleper season for total and productive females respectively. On somecommercial breeding farms birds are kept in lay for more than 9 months ayear. Males and females are separated during April and May. Improvementin egg production ability should be pursued by selection for the trait. Itwas learned from private communication that 75 eggs by individual femaleswere recorded on established breeding farms (Schmitt 1990) indicating thatbreaking of the pause after 15 consecutive eggs was achieved usingselection methods. The use of artificial light would be a useful tool instimulating the breeding birds to extend the laying season or to manipulatepattern of lay to two seasons per year as was demonstrated by Olver et al(1970) for geese. (See Fig. 8).

An integral part of stimulus for improved egg production, apart fromnutritional aspects that will be dealt with next, is the daily collectionof eggs. In natural breeding in the wild approximately 21 eggs are foundin one nest. It is deduced from observations in Zimbabwe (Jarvis et al1985) who reported an average of 13, Hurxthal (1979) in Kenya, 35 to 47 andSauer (1966) in Namibia, 16 to 23 eggs per nest. Normally more than one

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female would contribute to this clutch and each female laid not more than 8or 9 in each nest. Removing all but one or two eggs regularly counteractsthe instinct of broodiness, thus enhancing potential for egg production.Nidification includes some rituals such as selection of a site for the nestand preparing it (scraping) by the male and soliciting by the male andfemale. No pair bonding was found with ostriches. There appears to be adominant female which undertakes most or all of the daytime incubation of

Breedinq bird nutrition

Sexual maturity can take as long as 4 years to attain (Hurxthal 1979)but domesticated ostriches given the adequate quantities of nutrientsrequired to develop can be ready for breeding in just over 2 years of age(Osterhoff 1979). The accretion of body substance is relatively smallafter 14 months and can be considered equal to maintenance. Depending onwhen the bird hatched the changes in preparation of sexual activitiesspecifically in females has to be taken into consideration as the firstbreeding season, after the age of 2 years, approaches. Estimates of thenutrient requirements for egg production can be made using information likeegg mass, frequency of lay and composition of the egg. More importantthough is to know the onset of formation of structures related to eggproduction eg. the oviduct and follicle development in the ovary. It isalso necessary to anticipate the increased requirements for minerals,mainly calcium, amino acids, vitamins and energy, before the first egg isformed. King (1972) demonstrated with the aid of a sine model that thepeak energy expenditure in egg production for birds laying in clutches isdetermined by the overlap among cycles for individual eggs (period ofsynthesis for a single egg including follicular growth in days), the rateof production and the clutch size. King (1972) cited the period offollicular growth in the domestic fowl as 7 - 8 days. The period forostriches is not known and could be 16 days in which case the demand foradditional nutrients would start 18 days before the first egg is laid. Thedemand on extra nutrients would increase in a sigmoidal pattern reaching amaximum approximately 8 days before the first egg is laid. From that pointin time the nutrient requirements for egg production would remain at theplateau level until a laying day is skipped. The quantity of a nutrientwhile the plateau remains is independent of the time taken for eggformation and is only dependant on the quantity of nutrient in each egg.In the case of an ostrich it amounts to half an egg per day since an egg islaid only every second day. Synchronization of commencement of egg layingand timing of supply of additional nutrients is necessary. Dailyrequirement for amino acids by breeding ostriches were calculated and thevalues are shown in Table 3. The amino acids determined in egg protein isgiven in Table 4.

The requirement of amino acids for maintenance was taken to be thesame as that for protein growth in these calculations. This is a pointthat should be investigated. Fisher (1989) used different amino acidprofiles for proteins required for maintenance and for growth to calculatethe amino acids required for poultry.

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Table 3 Requirement for some amino acids of breeding ostriches inproduction

TABLE 4 Amino acid composition of ostrich egg and chicken( g per 16 g N 1

It will be noted that the size of the egg alters the dailyrequirement for amino acids considerably while an increase in bird size of5 kg has lesser effect. Decrease in production rate or skipping a few dayswould have a great effect. Changing the daily allocation of feed inaccordance with the observed pattern of lay would compensate for eitherover-consumption, which may cause fattening, or inefficiency which is theresult of unnecessary feed input with no output in return. The estimatedrequirement for energy is shown in Table 5.

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Table 5 Estimated energy requirement (MJ per day) for egg production ofthe ostrich in breeding pens (0.25 hectare)

A calcium supplement in the form of grit offers a choice to thefemales. The dietary calcium level then need not be very high althoughsufficient quantities of vitamins and minerals should be supplied in thediet, as well as linoleic acid. It should be investigated whetherostriches have a specific requirement for beta-carotene as has been shownrecently for turkeys (Stevens et al 1989). The breeding diet is totallyinappropriate for the males but it is very difficult to find a practicalway around this dilemma. The male could be fed separately in a fenced offarea in the pen and they can be let in for mating every second day. Thiswould prevent males from becoming overweight and likely reduced fertility.

Practical animal manaqement for adults

Individual birds behave differently and some birds, particularlymales in the breeding season, may show aggressive behaviour. A personentering a pen should carry a 2.5m long forked stick with a black plasticbag attached to the end. When planning the pen layout, construct fences 2m high, using seven strands of barbless wire with the bottom wire highenough above the ground to serve as an escape route if necessary(Thornberry 1989). In some areas ostrich ranch farming may be thepreferred method of breeding. The mating ratio in this case is 3 to 4females to a male bird. Mesh wire should then be used in addition tonormal fencing to keep predators out. Loading chutes and catch pens shouldbe constructed of solid wood, 2.5 meters high to prevent birds injuringthemselves. A hood fitted loosely over the head is an acknowledged methodto manipulate a bird after it has been hooked by the neck with a speciallydesigned U-shaped rod fixed to the end of a 3 m stick .

Hatchinq and survival

Ostrich chicks are typically precocious at hatching, which may lastfor 10 hours after piping and after 36 hours they are completely mobile.They are very dependent on their parents to learn to feed adequately. Mostfarmers collect eggs from the nests and use incubators that have been

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adapted to hatch the ostrich eggs. Thus the stimulus of seeing the parentsfeeding which is necessary for chicks to respond and learn to feed, will beabsent and this void has to be fulfilled by management. Hatching ofostrich eggs has been studied and documented (Jarvis et al 1985 ; Swart1988 ; Bertram et al 1981) and hatchability of fertile eggs as high as 85%can be expected. Shade in the breeding pen, observing and monitoringmating activity, regular collection and proper handling of eggs andtreatment of eggs before setting, including preheating, are all factorsthat could enhance the yield of chicks from the eggs produced. Normalhatchery hygiene must be practised.

Collected eggs should be cooled to 16oC as soon as possible and setwithin 2 to 5 days. Longer storage will reduce hatchability.

Field observations in a natural African habitat showed a variable buton average poor survival during two seasons of 36.9 and 43.4 % to 16 weeksof age (Hurxthal 1979). Poor survival, probably as a result of poormanagement, does occur on some farms but on the other hand reports fromsuccessful farmers state survival of 90% and more to 16 weeks of age.

CONCLUSIONS

We are faced with many unanswered questions about nutrition andmanagement of ostriches. A few may be mentioned: Body composition of maleand female birds, of different genotypes, should be determined. Thecoefficients for conversion of dietary amino acids to body substance andeggs have to be determined experimentally, also the question of whether theamino acid requirement for maintenance and growth differs significantly andwarrants separate attention, has to be addressed. At the same time thehypothesis, that ostriches' requirements include essential amino acids,could be tested by measuring the response of graded levels of particularamino acids. De novo appearance of amino acids in sections of thealimentary tract is not excluded. An important aspect of estimates aspresented in this paper is to know the confidence intervals of theestimates and the variables exerting an influence. Five to ten birds of abody size need to be slaughtered to determine the variation, especially atmaturity. This data could also be used to fit a Gompertz curve to proteingrowth. The values of all constants used in quantitative energy metabolismcalculations need to be confirmed with ostriches. The comfortable thermalenvironment for the ostrich has to be investigated since all theoreticalcalculations involving energy metabolism, are dependant on it. Energyexpenditure for activities eg. walking, browsing and feeding at a troughare not known.

Last, but not to be ignored is the routine evaluation of theavailability of nutrients in feedstuffs used to formulate ostrich diets:a formidable task !

I would like to express my appreciation and thanks to Dr Mike Jarvisfor valuable comments during the editing of this document. His knowledgeand experience in the field of ostrich research made an essentialcontribution. Of no less value was the information I gathered fromcommunication and contact with farmers and Dr D Swart, to whom I convey mysincere appreciation. I thank A Adams for technical assistance andlaboratory work.

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